The present disclosure relates to improved vehicle back doors, and specifically to a resin door inner panel having improved rigidity, the resin door inner panel having an upper section supported to an upper section of a rear end of a vehicle body through a pair of hinges.
A typical hatchback vehicle, e.g., having a back door opening on a rear end of a vehicle body of the hatchback vehicle includes a back door that can rotate vertically to open and close the back door opening. Such a back door includes an upper half portion equipped with a window pane. Hinge attachment locations are provided above the window pane. The back door is coupled with an upper section of a rear end of a vehicle body through hinges mounted on the hinge attachment locations. A user lifts up a lower section of the back door to open the back door opening, and pushes down the lifted back door to close the back door opening.
In closing the back door opening, one of the right end portion or the left end portion of the lower section of the back door may be pushed down. In this case, the load is applied on one of the right end portion or the left end portion of the lower section of the back door. In this case, the shape of the upper half portion of back door can be kept because a relatively highly rigid window pane is mounted. However, the lower half portion of the back door might be deformed by the load applied on one of the right end portion or the left end portion because a member such as a rigid window pane is not mounted. Various solutions were provided to reduce such deformation.
Japanese Unexamined Patent Publication No. 2012-101740 (paragraphs 0010, 0011, and 0012; and FIGS. 1 and 2) discloses a back door including a generally rectangular resin inner panel and a generally rectangular resin outer panel assembled to the inner panel. A rectangular reinforcing member, which is a metal pipe, is mounted on a surface of the inner panel along an outer periphery of the inner panel. This surface faces the outer panel. The reinforcing member secures the rigidity and reduces the deformation described above.
However, the back door of Patent Document 1 is equipped with the metal reinforcing member, and has unnecessary weight. This back door also inconveniently causes a trouble in mounting the reinforcing member.
It is an object of the present disclosure to increase the rigidity of a back door without an increase in the weight thereof, and reduce the deformation of a lower half portion of the back door.